Which of the following correctly describes a difference between the vegetal
pole of a frog zygote and the animal pole?
The vegetal pole of a frog zygote is distinct from the animal pole in several
key aspects:
-
Cytoplasm Composition: The vegetal pole contains a larger proportion
of yolk, a nutrient-rich substance that serves as a source of energy for
early embryonic development. In contrast, the animal pole has a higher
concentration of active cytoplasm, which is responsible for cell division
and differentiation.
-
Cell Division Rate: Cells in the vegetal pole divide more slowly than
those in the animal pole. This difference in cell division rate contributes
to the establishment of the dorsal-ventral axis of the embryo, with the
animal pole forming the dorsal (back) side and the vegetal pole forming the
ventral (belly) side.
-
Pigmentation: In some frog species, such as Xenopus laevis, the
animal pole is heavily pigmented, while the vegetal pole remains
unpigmented. This pigmentation pattern is thought to play a role in
establishing polarity and guiding early embryonic development.
-
Fate: The vegetal pole gives rise to extraembryonic structures, such
as the yolk sac and the gut tube, which support the developing embryo. The
animal pole, on the other hand, forms the ectoderm and mesoderm, which
eventually give rise to the skin, nervous system, muscles, and other tissues
of the embryo.
These differences between the vegetal and animal poles of a frog zygote are
crucial for establishing the basic body plan and initiating the intricate
processes of early embryonic development.
